I read that Starlog article- it all seems to hinge on this "figure" he thinks he can see near the start of the movie in the carpark.
Now I've probably seen BTTF over 20 times and have never noticed this, so I got out the blu ray and tried to spot what he's talking about...... jesus you could watch that film a thousand times and never notice that. I *think* there's someone there I guess, for about 2 frames. It's obviously certainly not intentional.